YouTube's audience has increased by 84% from 5.4m in October 2006 to 9.9m in October 2007, allowing it to jump up six spots to take eighth place in Nielsen's ranking. Wikipedia's audience increased by 50% from 6.3m to 9.5m, moving it up three places to number 10.
Apple and Microsoft were the only brands among the current top 10 to have experienced a drop in audience, losing 6% to 9.6m and 3% to 17m respectively.
The six most popular brands remain the same with Google retaining the top spot, followed by MSN/Windows Live, Microsoft, Yahoo!, BBC and EBay.
Alex Burmaster, internet analyst at Nielsen Online, said: "The story of the last year has, undoubtedly, been the phenomenal growth in user-generated content so it’s not surprising to see this reflected in the leading brands. Gone are traditional powerhouses like Real and AOL, being replaced by signature 'Web 2.0' brands such as YouTube and Wikipedia."
Nielsen Online also revealed that five of the 10 fastest growing online brands over the last year in the UK relate to social and professional networking. Rock You!, which provides applications and widgets for social networks, was the fastest growing online brand, with its audience increasing 2,106% to 1.9m between October 2006 and October 2007.
Facebook was the second fastest growing, up by 1,646% to 7.8m, followed by another provider of applications and widgets for social networks, Slide, which registered a 649% increase to 3.2m.
Overall, the 10 fastest growing online brands contain three social networking tools, one social network and one professional network.